What is the relationship between smoking and cancer

What are the harmful substances in tobacco?

What is the relationship between smoking and cancer
What is the relationship between smoking and cancer

The smoke produced by cigarette combustion contains at least more than 3000 harmful components, including polycyclic aromatic benzopyrene, 1,2-benzoanthracene, nitrosamine, polonium-210, cadmium, arsenic β- Naphthylamine has carcinogenic effects, and the cancer promoting substances in cigarette smoke include cyanide, o-cresol, phenol, etc. When smoking, most of the cigarette smoke is inhaled into the lungs, and a small part enters the digestive tract together with saliva. Some harmful substances in smoke stay in the lungs, and some enter the blood circulation and flow to the whole body. Under the synergistic action of carcinogens and cancer promoters, normal cells are damaged and cancer is formed.

Harmful components in cigarette smoke include alkaloids such as carbon monoxide and nicotine, amines, nitriles, alcohols, phenols, alkanes, alkenes, carbonyl compounds, nitrogen oxides, polycyclic aromatic hydrocarbons, heterocyclic compounds, heavy metal elements, organic pesticides, etc.
They have a variety of biological roles, including:

  • inflammatory stimuli to respiratory mucosa: such as aldehydes, nitrogen oxides, alkenes.
  • toxic effects on cells: such as nitriles, amines, heavy metals.
  • addictive effects: alkaloids such as nicotine.
  • Carcinogenic to humans: Such as benzopyrene in polycyclic aromatic hydrocarbons, as well as cadmium, dimethylnitrosamine, and β-naphthylamine.”
  • have cancer promoting effects on human body: such as phenolic compounds.
  • make red blood cells lose oxygen carrying capacity: such as carbon monoxide.

The content of harmful substances in tobacco is usually evaluated by “smoke tar and carbon monoxide”. It is required that the smoke tar produced by each cigarette is less than 15 mg, and the actual smoke on the market is more than several times. According to 20 cigarettes a day, a quarter of which are inhaled into the body, the amount of smoke tar inhaled by smokers is about 120~200 mg per day. The joint effect of harmful substances in smoke tar is a major threat to human cancer.

Harmful components in cigarette smoke:

Nicotine (particulate):

each cigarette contains about 1.5 mg, which makes smoking addictive. A small amount of nicotine plays an excitatory and stimulatory role, while a large amount of nicotine plays an inhibitory or paralytic role, with severe toxicity. The lethal dose is 40-60 mg. The bronchial mucosa is damaged and prone to inflammation and infection. It accelerates heart rate, increases blood pressure and arteriosclerosis, and promotes the occurrence of cardiovascular and cerebrovascular diseases.

Cigarette tar (particulate):

each cigarette contains 20-30 mg of carcinogens and cancer promoting substances. Cigarette tar is composed of phenol, aliphatic hydrocarbon, polycyclic aromatic hydrocarbons, acids, indole, pyridine and other concentrates. It often adheres to the throat, bronchus and alveoli and accumulates for many years, forming cancer.

Carbon monoxide (gas):

each cigarette can produce 20-30 ml of carbon monoxide, which destroys the oxygen carrying function of red blood cells, exacerbates hypoxia, and harms the cardiac and cerebral vascular systems. A series of organs of smokers will also produce pathological changes due to hypoxia. Promote the increase of cholesterol storage and accelerate atherosclerosis.

Radioactive substances (carcinogenic):

in tobacco fields, uranium rich phosphate fertilizer is applied, and uranium decomposes into radioactive needles, paving, atmosphere, etc. This radiation is harmful to human body and can lead to cancer. Radioactive needles are the most harmful, followed by radon, a derivative of pickaxes.

Direct carcinogens and others:

a cigarette contains about 100 nanograms of 3,4 benzopyrene and about 1-2 micrograms of cadmium, of which about 5% is absorbed by the human body, which has a strong carcinogenic effect. Other toxicants include hydrogen cyanide, acrolein, carbon monoxide, formic acid, etc.

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